There are 3 ways that is possible.
If you go to the WIN from start, you can either go to another win then a loss, or vice versa. There is 2 ways if you win the first game.
If you loose the first game, then you have to win the second and third to only has 1 loss. That's the only way you can go for 1 loss if you loose the first game.
Together, that's 3 ways: WWL, WLW, and LWW